Abstract
For human beings, environments in space are extremely different from those on earth. It is, therefore, important to elucidate biological influences of space environmental factors for promoting a utilization of space environments. Here, we report the results of experiments for estimating the space-radiation effects by using human lymphoblastoid TK6 cells, which were preserved as a frozen state in the Kibo module of International Space Station (134 days in space, 72 mSv).
In our post-flight assay, a radiation-sensitive methodology, LOH (Loss of Heterozygosity) analysis, was applied for detecting and characterizing the mutants at both levels of gene and chromosome, which could be considered to be caused by low-dose space radiation. In addition, the recovered cells were exposed to challenging X-rays (2 Gy) and the obtained mutants were also analyzed by the LOH methodology for elucidating the possibility that the radiation damage accumulated during the space flight could express the radioadaptation when the cell were incubated after the recovery (suppression of X-ray induced mutation). Furthermore, we examined an enhanced efficiency of repair of chromosomal DNA double-strand breaks created by the I-SceI vector infection of the recovered cells. The observed results support the possibility that the cells exposed to space radiation exhibit both mutation-induction and radioadaptation.
